Strato Sfera Labs Strato Pi cm Duo User guide

Brand: Strato

Model: Sfera Labs Strato Pi cm Duo

Type: User guide

Strato Pi CM Duo User Guide

September 2019

Revision 001

SCMD10XS Strato Pi CM Duo Solo

SCMD10XPL Strato Pi CM Duo 3+ Lite

SCMD10XP1 Strato Pi CM Duo 3+ 8GB

SCMD10XP2 Strato Pi CM Duo 3+ 16GB

SCMD10XP3 Strato Pi CM Duo 3+ 32GB

Safety information 4
Qualiﬁed personnel 4
Hazard levels 4
Safety instructions 5
General safety instructions 5
Battery 6
Introduction 7
Features 8
Device identiﬁcation 9
Hardware Installation 9
Opening the case 10
Closing the case 10
Raspberry Pi Compute Module installation 10
How to ﬂash the eMMC 11
microSD installation 11
Replacing the RTC backup battery 12
Terminal block 14
Power supply 14
Dedicated GPIO pins 15
Software installation and conﬁguration 16
Installing the Strato Pi utility on Raspbian 16
Installing the Strato Pi kernel module 16
Enabling the second SD interface 17
Installing the Real Time Clock software 17
Testing the Real Time Clock 17
Using Strato Pi CM Duo 19
Real Time Clock 19
RS-485 serial port 19
SD matrix 20
USB ports power management 22
ATECC608A secure element 23
Push button 24
LED 24
Hardware watchdog 24
Reset cycle 25
Advanced conﬁguration 25
1
Strato Pi CM Duo User Guide

Block diagram 27

Technical speciﬁcations 28

Dimensions 29

Disposal 30

Installation and use restrictions 30

Standards and regulations 30

Safety instructions 30

Set-up 30

Conformity Information 31

EU 31

USA 31

CANADA 32

RCM AUSTRALIA / NEW ZEALAND 32

Strato Pi CM Duo User Guide

Be sure to always remove the power supply before inserting or

removing the Raspberry Pi Compute Module from the Strato Pi CM Duo.

Follow all applicable electrical safety standards, guidelines,

speciﬁcations and regulations for installation, wiring and operations of

Strato Pi CM Duo.

Carefully and fully read this Strato Pi CM Duo user guide before

installation.

Strato Pi CM Duo is not authorised for use in safety-critical applications where a failure of

the product would reasonably be expected to cause personal injury or death. Safety-critical

applications include, without limitation, life support devices and systems, equipment or

systems for the operation of nuclear facilities and weapons systems. Strato is neither

designed nor intended for use in critical military or aerospace applications or environments

and for automotive applications or environment. Customer acknowledges and agrees that

any such use of Strato Pi CM Duo is solely at Customer's risk, and that Customer is solely

responsible for compliance with all legal and regulatory requirements in connection with

such use.

Sfera Labs S.r.l. may make changes to speciﬁcations and product descriptions at any time,

without notice. The product information on the web site or materials is subject to change

without notice.

Please download and read the Sfera Labs Terms and Conditions document available at:

https://www.sferalabs.cc

Strato and Sfera Labs are trademarks of Sfera Labs S.r.l. Other brands and names may be

claimed as the property of others.

Strato Pi CM Duo User Guide

Safety information

Carefully and fully read this user guide before installation and retain it for future reference.

Qualiﬁed personnel

The product described in this manual must be operated only by personnel qualiﬁed for the

speciﬁc task and installation environment, in accordance with all relevant documentation

and safety instructions. A qualiﬁed person should be capable of fully identifying all

installation and operation risks and avoid potential hazards when working with this product.

Hazard levels

This manual contains information you must observe to ensure your personal safety and

prevent damage to property. Safety information in this manual are highlighted by the safety

symbols below, graded according to the degree of danger.

Indicates a hazardous situation which, if not avoided, will result in death or serious

personal injury.

Indicates a hazardous situation which, if not avoided, may result in death or serious

personal injury.

Indicates a hazardous situation which, if not avoided, can result in minor or moderate

personal injury.

Indicates a situation which, if not avoided, can result in damage of property.

DANGER

WARNING

CAUTION

NOTICE

Strato Pi CM Duo User Guide

Safety instructions

General safety instructions

Protect the unit against moisture, dirt and any kind of damage during transport, storage

and operation. Do not operate the unit outside the speciﬁed technical data.

Never open the housing. If not otherwise speciﬁed, install in closed housing (e.g.

distribution cabinet). Earth the unit at the terminals provided, if existing, for this purpose.

Do not obstruct cooling of the unit. Keep out of the reach of children.

Life threatening voltages are present within and around an open control cabinet.

When installing this product in a control cabinet or any other areas where dangerous

voltages are present, always switch off the power supply to the cabinet or equipment.

Risk of ﬁre if not installed and operated properly.

Follow all applicable electrical safety standards, guidelines, speciﬁcations and regulations

for installation, wiring and operations of this product.

The Raspberry Pi Compute Module board could generate a substantial amount of heat

when the software forces the CPU and/or GPU to operate at high load levels. Ensure that

the product is properly installed and ventilated to prevent overheat.

The connection of expansion devices to this product may damage the product and other

connected systems, and may violate safety rules and regulations regarding radio

interference and electromagnetic compatibility.

Use only appropriate tools when installing this product. Using excessive force with tools

may damage the product, alter its characteristics or degrade its safety.

WARNING

NOTICE

Strato Pi CM Duo User Guide

Battery

This product uses a small lithium non-rechargeable battery to power its internal real time

clock (RTC).

Improper handling of lithium batteries can result in an explosion of the batteries and/or

release of harmful substances.

Worn-out or defective batteries can compromise the function of this product.

Replace the RTC lithium battery before it is completely discharged. The lithium battery

must be replaced only with an identical battery. See the "Replacing the RTC backup

battery" section for instructions.

Do not throw lithium batteries into ﬁre, do not solder on the cell body, do not recharge, do

not open, do not short-circuit, do not reverse polarity, do not heat above 100°C and protect

from direct sunlight, moisture and condensation.

Dispose of used batteries according to local regulations and the battery manufacturer's

instructions."

WARNING

Strato Pi CM Duo User Guide

Introduction

Strato Pi CM Duo is an extremely powerful and compact industrial server based on the

Raspberry Pi Compute Module, suitable for use in professional and industrial applications

where reliability and service continuity are key requirements, and housed in a compact 2

modules DIN rail case.

It is available in several versions. Strato Pi CM Duo 3+ ships with a Raspberry Pi Compute

Module 3+ (8GB, 16GB or 32GB eMMC versions) pre-installed, while Strato Pi CM Duo

Solo doesn't include the Compute Module and is compatible with all current versions of the

Compute Module: 1, 3, 3 Lite, 3+ and 3+ Lite.

The information contained in this manual covers both Strato Pi CM Duo 3+ and Strato Pi

CM Duo Solo. Besides the fact that Strato Pi CM Duo 3+ has the Compute Module pre-

installed, all versions are otherwise identical.

This manual generally refers to all products as Strato Pi CM Duo.

Strato Pi CM Duo User Guide

Features

Strato Pi CM Duo, all versions:

✓

compatible with Raspberry Pi Compute Module 1, Raspberry Pi Compute Module 3,

Raspberry Pi Compute Module 3 Lite, Raspberry Pi Compute Module 3+ 8GB,

Raspberry Pi Compute Module 3+ 16GB, Raspberry Pi Compute Module 3+ 32GB,

Raspberry Pi Compute Module 3+ Lite

✓

9-28Vdc power supply, with surge and reverse polarity protection, and 1.1A resettable

fuse

✓

up to 1.9A max continuous current (3A peaks) to the 5V Raspberry Pi Compute Module

power supply input pins (at 24Vdc)

✓

real time clock with replaceable CR1220 Lithium / Manganese Dioxide back-up battery

✓

standard RS-485 interface to the Raspberry Pi serial line, with opto-isolator and

electrostatic discharge protection

✓

10/100 Ethernet port

✓

two USB 2.0 type-A ports, with individual power control and fault detection

✓

dual microSD card architecture. Strato Pi CM routes its two microSD card holders to

the Compute Module through a high-speed switching matrix, controlled by the on-board

micro-controller. Each SD card can be set as the boot card, with the other available as

additional storage. This enables for separate OS/data storage, SD redundancy and in-

ﬁeld full-system upgrades. The microSD slots are hidden, and can be accessed

opening the case

✓

hardware watchdog implemented in the Strato Pi CM Duo micro-controller, fully

independent from the Raspberry Pi Compute Module, controlled via the GPIO pins of

the Raspberry Pi board and acting on the Raspberry Pi Compute Module hardware

reset line. The hardware watchdog can also control the microSD switch matrix,

swapping the boot card in case the watchdog is triggered

✓

integrated boot loader for the Strato Pi micro-controller, allowing in-ﬁeld ﬁrmware

upgrades directly from the Raspberry Pi

✓

embedded Microchip ATECC608A secure element chip

✓

front-panel LEDs for power supply, serial line activity, and one GPIO-controlled LED

✓

recessed push-button, hidden behind the front-panel, connected to a GPIO pin

✓

power supply and serial connections on a pluggable terminal block

✓

packaged in a compact 2 modules DIN rail case.

Strato Pi CM Duo 3+:

✓

pre-installed and tested Raspberry Pi Compute Module 3+, Lite, 8GB, 16GB or 32GB

eMMC versions.

Strato Pi CM Duo User Guide

Device identiﬁcation

The device can be identiﬁed with the information provided in the rating and identiﬁcation

plate, permanently attached to the side of the case.

EXAMPLE RATING AND IDENTIFICATION PLATE

Hardware Installation

STRATO PI CM DUO CONNECTION DIAGRAM

For the initial set-up, the plastic DIN rail must be removed to access the circuit boards and

internal connectors.

The case also needs to be opened if the factory conﬁguration of the RS-485 termination

resistors must be changed (see below).

Strato Pi CM Duo User Guide

Before opening the Strato Pi Base case, disconnect all power sources and any connection

to external devices, including USB and Ethernet cables.

Opening the case

Follow these steps, in the exact order, to open the case:

1. Remove the green pluggable terminal block

2. Remove the black plastic DIN rail hook

3. With a small ﬂat screwdriver gently separate the bottom case and boards assembly

from the top cover; lift the side next to the DIN rail hook ﬁrst

4. The circuit boards assembly will simply slide out of the case, as it is mechanically held

in place by the bottom case only

Closing the case

5. Replace the circuit boards assembly inside the case; ensure that the USB/Ethernet

connectors are aligned with the opening in the case

6. Replace the case bottom, inserting the side opposite to the DIN rail hook ﬁrst, then

gently push the other side in place

7. Replace the black plastic DIN rail hook.

OPENING AND CLOSING THE CASE

Raspberry Pi Compute Module installation

To install your own Compute Module in Strato Pi CM Duo Solo, or replace the pre-installed

module in Strato Pi CM Duo 3+, no tools are required. The Compute Module ﬁts in a

standard 200 pin DDR2 SODIMM (JEDEC MO-224 mechanical speciﬁcation) slot.

NOTICE

Strato Pi CM Duo User Guide

Static electricity can damage the components in your system. To protect your system's

components from static damage during the installation process, touch any of the unpainted

metal surfaces on your computer's frame or wear an ESD wrist strap before handling

internal components. Either method will safely discharge static electricity that's naturally

present in your body.

When handling the Raspberry Pi Compute Module, be sure to hold it along the side edges

using your thumb and index ﬁnger. Avoid touching the components and pin connectors as

damage can occur.

Align the notches on the Compute Module with the ridges in the DDR2 slot. Insert the

module using ﬁrm and even pressure, and push down on the module until the clips on the

side of the slot snap into place.

How to ﬂash the eMMC

The Compute Module versions 1, 3 and 3+ have an on-board eMMC device connected to

the primary SD card interface.

In order to ﬂash the Compute Module's eMMC memory, an additional board, like the

Compute Module IO Board V3, must be used.

microSD installation

Strato Pi CM Duo has two microSD slots to install ﬂash memory cards.

When the Compute Module Lite is installed, as it lacks an internal eMMC chip, one of the

two microSD slots will be used as the boot SD card, just like with a Raspberry Model B

board. The other microSD can be used as additional storage. Dedicated commands to the

micro-controller allow to select which slot is used for boot, and if the other is enabled or

not.

When a Compute Module with embedded eMMC is installed, both microSD slots can be

used as additional storage. You can only access one SD card at a time, but the active card

can be selected sending the appropriate commands to the micro-controller.

The microSD slots are not directly accessible with the case closed. The slots are located

on the vertical board, next to the USB/Ethernet modular connector.

The bottom slot is SDA, and the top is SDB.

NOTICE

Strato Pi CM Duo User Guide

MICRO SD SLOTS

Replacing the RTC backup battery

Strato Pi CM Duo has a hardware real time clock with a dedicated long-life non-

rechargeable back-up battery.

Strato Pi CM Duo is shipped with a CR1220 Lithium / Manganese Dioxide (Li/MnO2)

battery installed.

The battery is only used to power the RTC chip when the main power is not available.

Depending on operating conditions it should last up to two years if the Strato Pi CM Duo is

not powered, more if it regularly receives external power.

The RTC backup battery holder is on the vertical circuit board, opposite the Compute

Module slot. In the Strato Pi CM Duo, the battery is not accessible from the outside. You

should ﬁrst remove the case body to gain access to the Strato Pi CM Duo circuit boards.

Follow the procedure described at the beginning of this chapter to open and replace the

case.

Improper handling of lithium batteries can result in an explosion of the batteries and/or

release of harmful substances.

Worn-out or defective batteries can compromise the function of this product.

KEEP OUT OF REACH OF CHILDREN. Swallowing may lead to serious injury or death in

as little as 2 hours due to chemical burns and potential perforation of the esophagus.

Immediately see doctor.

WARNING

BR1220 batteries (Lithium Poly-carbonmonoﬂuoride) can also be used, for improved shelf and

service life.

Strato Pi CM Duo User Guide

Replace the RTC lithium battery before it is completely discharged. Replace the battery

every 5 years even if the battery is still working properly. The lithium battery must be

replaced only with an identical CR1220 or BR1220 battery.

Do not throw lithium batteries into ﬁre, do not solder on the cell body, do not recharge, do

not open, do not short-circuit, do not reverse polarity, do not heat above 100°C and protect

from direct sunlight, moisture and condensation.

Dispose of used batteries according to local regulations and the battery manufacturer's

instructions.

Before opening the Strato Pi Base case, disconnect all power sources and any connection

to external devices, including USB cables.

Use a non-conductive pin or small tool to help extract the battery from its holder. Insert the

new battery with a gentle push. You don't need tools to insert the battery. The battery is

held into place by a spring contact.

Be sure to insert the battery so that the negative (-) terminal is facing the vertical circuit

board, and touches the contact pad at the center of the battery holder, as shown in the

photo below.

Reversing the battery polarity may damage the product.

The real time clock will reset its time immediately when the RTC backup battery is

disconnected.

RTC BACKUP BATTERY HOLDER

RTC BACKUP BATTERY INSTALLED

NOTICE

Strato Pi CM Duo User Guide

Terminal block

Strato Pi CM Duo has a 5 positions terminal block for power and serial connections.

The maximum conductor cross section is 1.5 mm

(16 AWG), or 0.5 mm

when using

ferrules (highly recommended). Recommended stripping length is 5 mm. Screw thread is

M2. Never exceed 0.25 Nm torque when tightening the screws.

Power supply

Strato Pi CM Duo can be powered with DC voltage only:

✓

DC: nominal voltage range 9V to 28.0V.

Respect the correct polarity shown in the schematic diagram (+ -). The power supply

circuit implements reverse polarity protection using an auto resetting fuse and surge

protection up to ±1000V/2ohms 1.2/50μs.

A blue on-board LED, also visible through the front panel of the DIN rail case, is lit when

power supply is available. This LED also blinks while the Compute Module boot process is

in progress.

The Strato Pi CM Duo power supply stage is optimised to deliver up to 1.9A at 5V to the

Raspberry Pi Compute Module.

The voltage regulator can supply up to 3.0A 5V output short duration current peaks

(<1sec).

Because Strato Pi CM Duo has a 1.1A resettable fuse (polyfuse) on the power supply line,

the maximum current that its regulator can deliver is also limited by this fuse, and depends

on the input voltage.

The following table lists the typical measured output current of the power supply stage at

different input voltages, and the corresponding input current. At high input voltage levels,

the voltage regulator’s thermal protection becomes the limiting factor.

STRATO PI CM DUO POWER SUPPLY STAGE TYPICAL IN/OUT VOLTAGE AND CURRENT

FUSE marks the level where the polyfuse opens to limit input current; REG is the voltage

regulator's thermal protection limit.

Strato Pi CM Duo User Guide

Dedicated GPIO pins

Strato Pi CM Duo uses some of the Raspberry Pi Compute Module GPIO pins. These pins

should not be used for other functions.

GPIO pin

Direction

Description

GPIO2/SDA

C SDA line for the real time clock

GPIO3/SCL

C SCL line for the real time clock

GPIO14/TXD

out

serial TX line

GPIO15/RXD

serial RX line

GPIO32

out

cycle high/low for watchdog heartbeat

GPIO39

out

set to high to enable the watchdog

GPIO17

high on watchdog timeout

GPIO18

out

set to high to enable the shutdown cycle

GPIO16

out

set to high to turn on LED L1

GPIO38

high when P1 button pressed

GPIO37

out

soft serial TX for Strato MCU conﬁguration

GPIO33

soft serial RX for Strato MCU conﬁguration

GPIO30

out

set to low to enable USB1 (bottom) power

GPIO0

low on USB1 fault

GPIO31

out

set to low to enable USB2 (top) power

GPIO1

low on USB2 fault

GPIO6

out

expansion bus enable (reserved for future use)

GPIO34

in/out

expansion bus aux/act line (reserved for future use)

Strato Pi CM Duo User Guide

Software installation and conﬁguration

All features of Strato Pi CM Duo are controlled via dedicated GPIO, the I

C bus and a soft

serial RX/TX interface to the embedded micro-controller and can be used with most

operating systems and programming languages.

The following software installation notes are based on the Raspbian operating system.

Installing the Strato Pi utility on Raspbian

The Strato Pi utility is a simple command-line script to control some of Strato Pi’s basic

functions.

Run the following commands to download and install the Strato Pi utility:

$ cd /usr/local/bin

$ sudo wget http://sferalabs.cc/files/stratocmduo/strato

$ sudo chmod 755 strato

You can run the Strato Pi utility without arguments to print its options:

$ strato

Usage: strato led on|off|length_millis|length_millis pause_millis repeats

strato usb1|usb2 on|off|fault

strato expbus on|off

strato watchdog enable|disable|heartbeat|timeout

strato reset

All commands should be run as superuser, so always use sudo to run strato.

Installing the Strato Pi kernel module

The Strato Pi kernel module can be used to easily access all of Strato Pi CM Duo control

features via a sysfs ﬁle system.

Run the following commands to download and install the Strato Pi kernel module (see

https://github.com/sfera-labs/strato-pi-kernel-module for detailed installation instructions):

$ sudo apt-get install git-core

$ git clone --recursive https://github.com/sfera-labs/strato-pi-kernel-

module.git

$ sudo apt-get install raspberrypi-kernel-headers

$ cd strato-pi-kernel-module

$ make

$ sudo make install

To have the module automatically loaded at boot add stratopi in /etc/modules:

$ sudo sh -c "echo 'stratopi' >> /etc/modules"

Optionally, to be able to use the /sys/ ﬁles not as super user, create a new group "stratopi"

and set it as the module owner group by adding an udev rule:

$ sudo groupadd stratopi

$ sudo cp 99-stratopi.rules /etc/udev/rules.d/

Strato Pi CM Duo User Guide

Then add your users to the group, e.g., for user "pi", and reboot:

$ sudo usermod -a -G stratopi pi

$ sudo reboot

Enabling the second SD interface

The SD1 interface must be enabled with the following line in the /boot/conﬁg.txt ﬁle:

dtoverlay=sdio,bus_width=4,poll_once=off

Installing the Real Time Clock software

The RTC is based on the Microchip MCP79410 module and is connected to the Raspberry

Pi via its I

C serial bus.

Before downloading the installation utility, you should enable I

C and install the “i2c-tools”

package.

To en ab le I

C, run the “raspi-conﬁg” conﬁguration utility:

$ sudo raspi-config

Then go to “Interfacing Options”, “I2C” and select “yes” to enable the I

C interface, then

reboot your Raspberry Pi.

To install the “i2c-tools” package:

$ sudo apt-get update

$ sudo apt-get install i2c-tools

With these prerequisite installs completed, you should download and run Strato Pi’s

installation script:

$ cd

$ wget http://sferalabs.cc/files/strato/rtc-install

$ chmod 755 rtc-install

$ sudo ./rtc-install

If the script completes with no errors, delete the installation script and reboot:

$ rm rtc-install

$ sudo reboot

Testing the Real Time Clock

Assuming you are connected to the Internet and your Pi was able to reach a public NTP

(Network Time Protocol) server, you should see the current date and time using the “date”

command:

$ date

Thu Dec 10 18:02:32 CET 2015

Also check the date and time stored in the hardware clock:

$ sudo hwclock -r

Thu 10 Dec 2015 06:03:01 PM CET -0.546570 seconds

Strato Pi CM Duo User Guide

If the returned date and time is not correct, or “hwclock” returns an error, use the “-w”

option to set the hardware clock to the current time:

$ sudo hwclock -w

Then recheck the time stored in the hardware clock to ensure it matches. Linux may have

failed to automatically update the hardware clock after the last reboot if its internal

registers contained invalid values.

If the RTC still doesn’t work, you should check if the Pi sees the RTC chip on the I

C bus.

Run these two commands:

$ sudo modprobe -r rtc_ds1307

$ sudo i2cdetect 1

WARNING! This program can confuse your I2C bus, cause data loss and worse!

I will probe file /dev/i2c-1.

I will probe address range 0x03-0x77.

Continue? [Y/n]

0 1 2 3 4 5 6 7 8 9 a b c d e f

00: -- -- -- -- -- -- -- -- -- -- -- -- --

10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

50: -- -- -- -- -- -- -- 57 -- -- -- -- -- -- -- --

60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6f

70: -- -- -- -- -- -- -- —

You should see “6f” in the address list. This is the address of the RTC.

If the RTC address is detected, double check your software installation for issues at the

Linux modules level.

Run the “lsmod” command to list the loaded modules and check that “i2c_dev” and

“i2c_bcm2708” are both listed.

If the RTC address is not detected, the cause could be a hardware problem, on the Strato

board or the Raspberry Pi. If you have another Pi or Strato board, try swapping them to

isolate the faulty board.

Strato Pi CM Duo User Guide

Using Strato Pi CM Duo

Real Time Clock

Strato Pi CM Duo has a hardware real time clock with a dedicated long-life non-

rechargeable back-up battery.

Once the RTC modules and conﬁguration ﬁles are properly installed, you will simply use

the date and time commands to control the hardware clock.

RS-485 serial port

Strato Pi CM Duo uses the Raspberry Pi standard UART TX/RX pins on the GPIO

connector to implement a standard RS-485 port.

The RS-485 port is isolated from the Raspberry Pi’s serial lines using dedicated opto-

couplers and from the main power supply with a high-efﬁciency DC-DC converter. This

conﬁguration should prevent ground loops between devices connected through the serial

line.

The RS-485 TX/RX switching is implemented automatically in the Strato Pi’s micro-

controller, based on speed and number of bits detection, and is completely transparent to

the software controlling the UART on Raspberry Pi. It can also be manually conﬁgured to

work with ﬁxed communication parameters (speed, bits, parity, stop bits) or in passive

mode (refer to the "Strato Pi Logic Controller Advanced Conﬁguration Guide" document for

additional information).

The RS-485 line has 620 Ohm pull-up and pull-down resistors on lines A and B. The

biasing resistors ensure that, during idle periods the data lines are kept at a stable voltage

level and prevent false triggering of receiver input. These resistors can be disabled by

removing jumpers JP1 and JP2 respectively.

A 100 Ohm termination resistor between A and B is connected when the J1 micro-switch is

moved toward the terminal block.

RS-485 JUMPERS AND SWITCH SCHEMATIC

Strato Pi CM Duo User Guide

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Strato Sfera Labs Strato Pi cm Duo User guide

Brand: Strato

Model: Sfera Labs Strato Pi cm Duo

Type: User guide

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